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Pregunta 1 Informe
Why does the treatment of cotton fabrics with dilute acids weaken the materials?
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Pregunta 3 Informe
What is the change in the oxidation number of phosphorus in the following reaction?
4P(s) + 5O2(ag) → 2P2O5(s)
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Pregunta 4 Informe
At s.t.p, a mole of chlorine occupies 22.4dm3. If the temperature is changed to 35°C and the pressure to 750mHg the of the new volume will be [Cl = 35.5]
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Pregunta 5 Informe
Small amounts of compounds of transition metals are sometimes added to glass during manufacture in order to make the glass
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Pregunta 6 Informe
What is the number of moles of NaHCO3in 250cm3 of its solution if the solution contains 8.4 g of NaHCO3 in 1 dm3 of the solution. [Na = 23, 0 = 16, C = 12, H = 1)
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Pregunta 8 Informe
What change will occur to the equilibrium mixture
\( 2CrO^{2-}_4(aq) + 2H^+(aq) ⇔ Cr_2O^{2-}_7(aq) + H_2O(l) \) when excess sodium hydrogen solution is added?
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Pregunta 9 Informe
What change will occur during the electrolysis of brine using carbon electrodes?
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Pregunta 10 Informe
What mass of copper is deposited when 6.5g of granulated zinc reacts with excess copper(II) tetraoxosulphate(VI) solution?
The equation for the reaction is: Zn(s) + \( CuSO_4(aq)→ ZnSO_4(aq)+ Cu(s)\)[CU= 64; Zn=65]
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Pregunta 11 Informe
Which statement is NOT true about the composition of starch?
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Pregunta 13 Informe
Which metal is a constituent of both bronze and solder?
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Pregunta 14 Informe
B is an isotope of the element \(^{238} _{92}Ur\). The isotope B has
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Pregunta 15 Informe
Naturally occurring lithium consists of 90% \( ^7_3Li \text{ and 10% } ^6_3 Li. \) What is the relative atomic mass of lithium?
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Pregunta 16 Informe
Which formula is used to indicate the degree of acidity of an acid?
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Pregunta 18 Informe
How many Faradays of electricity are required to liberate 9g of aluminium? [Al = 27]
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Pregunta 19 Informe
What mass of silver is deposited when a current of 2.6 A is passed through a solution of a silver salt for 40 minutes? [Ag= 108 ; F=96500C]
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Pregunta 21 Informe
An atom of element X has an electronic configuration of \( 1s^22p^33s^23p^2. \) In which group of the periodic table is X?
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Pregunta 26 Informe
Which compound will give propane when it Is dehy drated by an excess of hot, concentrated tetraoxosvlphate(VI) acid?
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Pregunta 27 Informe
Why is tetraoxosulphate(VI) acid NOT used for making carbon dioxide from calcium carbonate? It is
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Pregunta 28 Informe
Chlorine displaces bromine from aqueous potassium bromide because
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Pregunta 29 Informe
Which hydrocarbon does NOT exhibit structural isomerism?
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Pregunta 31 Informe
Which separation technique is routinely applied in the petroleum industry?
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Pregunta 32 Informe
What is the concentration (in mol dm3) of a solution containing 28 g of potassium hydroxide per 100 cm3 of solution? (K=39; H=1; 0=16)
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Pregunta 33 Informe
Ethene decolourises acidified potassium tetraoxomanganate(VII) solution. Which gas will decolourise bromine water?
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Pregunta 34 Informe
The number of hydrogen ions in 1.0dm6.00x103 of a 0.25 mole dm6.00x10-3 tetraoxosulphate(Vl) acid solution is
[Avogadro constant = 6.0 x 1 0]
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Pregunta 35 Informe
Which method is used for the purification of copper from its ore?
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Pregunta 36 Informe
In the reaction 2H2S(g) + SO2(g) → 2H2SO(I)+3S(s)SO2is acting as _agent
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Pregunta 37 Informe
An organic compound gave the following results on analysis: C = 29.3% ; H = 5.7%; Br = 65%.
What is the empirical formula of the compound? [C = 12, H = 1, Br=80]
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Pregunta 38 Informe
The boiling point of water is higher than the boiling point of ethanol because
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